Call charging telephone exchange system



24, 1932- 1.. H. JOHNSON ET AL CALL CHARGING TELEPHONE EXCHANGE SYSTEMFiled June 28, 1950 1O Sheets-Sheet 1 L; hf JOHNSON E 5' 5/as0/v May 24,1932. L. H JOHNSON ET AL 1,859,924

CALL CHARGING TELEPHONE EXCHANGE SYSTEM Filed June 28, 1930 10Sheets-Sheet 2 4 NOW I Dow Dem May 24, 1932.

L. H. JOHNSON ET AL CALL CHARGING TELEPHONE EEGHANGE SYSTEM Filed June28, 1930 10 Sheeis-Sheet 3 lg g IN VE N TUHS L. H. JOHNSON E 5'. 5/550By Q s/1w A T TUBA/E) May 24, 1932- L. H. JOHNSON ET AL 1,359,924

CALL CHARGING TELEPHONE EXCHANGE SYSTEM Filed June 28, 1950 10Sheets-Sheet 4 l5 I6 I718 BYy -d A 7' TOHNE May 24, 1932- 1.. H. JOHNSONET AL 1,859,924

' CALL CHARGING TELEPHONE EXCHANGE SYSTEM I Filed June 28, 1950 1oShets-Sheet 5 JIIHIR maa w A TTUENE Y y 1 L. H; JOHNSON ET AL 1,859,9247 CALL CHARGING TELEPHONE EXCHANGE SYSTEM FiIe d June 28} 1930 10Sheets-Sheet 6 Y 3 do use/v /NVNTOR5 May 24, 1932. H. JOHNSON ET AL 7 r4 CALL CHARGING TELEPHONE EXCHANGE SYSTEM 1 Filed Jun e 28/1930 ,10sneaks-sheet"? L. HUGH V50 v mEvmQNb E T U) v Ill U a Ill U 3} ll. [U 3.J E. III )ll. lnrlll-lll )L. U D] U al Ill Bk N. R WWW w U 5% w my 0.1w W9. W5 3w May 24, 1932. L JOHNSON ET AL 1,859,924

CALL CHARGING TELEPHONE EXCHANGE SYSTEM Filed June 28, 19:50 10Sheets-Sheet 9 ATTORNEY May 24, 1932- 1., H. JOHNSON ET AL 1,359,924

CALL CHARGING TELEPHONE EXCHANGE SYSTEM Filed June 28, 1930 10Sheets-Sheet l0 L hf Jam/saw E. 5'. G/BSDN 6 16. ama- /N 1/5 N TOHS A TTRNEY Patented May 24, 1932 UNITED STATES.

PATENT OFFICE- LEWIS H. JOHNSON, OF MADISON, AND EARL S. GIBSON, 0FRIDGEWOOD, NEW JERSEY, ASSIGNORS TO BELL TELEPHONE LABORATORIES,INCORPORATED, OF NEW YORK,

N. Y., A CORPORATION OF NEW YORK CALL CHARGING TELEPHONE EXCHANGE SYSTEMApplication filed June 28,

This invention relates to dial telephone systems and more particularlyto metering calls on multi-party telephone lines. The ob ect of theinvention is the attainment of more equitable compensation for the useof telephone facilities.

In large exchange areas having several oflices some of which may belocated at very distant points in the area, it is desirable that meansbe provided whereby a calling subscriber may be charged.,diflerently forcalls to oflices which are most remotely located from the office inwhich the calling line terminates, than for calls to oflices which arenot so remotely located since remotely located offices must be reachedover long interoflice trunks which are expensive to install andmaintainand it is not equitable to the operating company to provideservice to all points in the exchange area at the same basic rate. Furthern'iore, it is not equitable to the operating company that for abasic rate a subscriber shall be enabled to hold an establishedconnection indefinitely.

Both automatic charging in accordance with the zone of the exchange areainto which a connection has been extended and in accordance with theelapsed conversational period have been heretofore accomplished. Thecharging of calls on multi-party lines through the operation of a metercontrol device cominon to a group of calling lines has been cffected asdisclosed in Patent No. 1,778,309, granted Oct. 14, 1930 to W. WV.Carpenter and L. H. Johnson.

In accordance with the present invention one embodiment of which isdisclosed herein by way of illustration, provision has been made forcharging calls on multi-party lines by means of a common meter controldevice of the general character disclosed in the aforementionedapplication in accordance with the zone of the exchange area into whicha call has been extended and in accordance with the elapsed time duringwhich the connection is held for conversation. While the invention hasbeen illustrated in connection with subscribers lines having but twoparty stations. the invention is equally applicable to lines havingagreater number of stations 1930. Serial No. 464,442.

. 60 sage register terminal over which either party register may becontrolled. Each line finder of the group which has access to a group of400 subscribers lines is paired with a district selector by a linkcircuit. Individual to r each line finder-district link circuit there isprovided a timing switch circuit for measuring a predetermined initialperiod of conversation and for measuring overtime periods if theconversation between the calling line and a called line is continued.

Associated with the timing switch circuit are zone recording relayswhich are selective- 1y operated from the common register sender inaccordance with the zone of the exchange area into which a connection isextended. The sequence switch of the district selector also assumesdifferent positions dependent upon the zone into which the connection isestablished and cooperates with the zone recording relays to establishin the timing switch circuit a record of which of six zones the calledline terminates in. Common to all of the line finder-district linkswhich serve a group of 400 lines, a message register connector circuitis provided. This common circuit is equipped with a plurality of sets ofmulti-contact relays, each set serving to connect with all of themessage registers of corresponding party stations. Thus, for example,one set of relays is arranged to connect with all of the registers ofthe J stations and the other set of relays is arranged to connect withall of the registers of the stations of the group of 400 lines.Associated with the common connector circuit is a plurality of partydesignating relays which are selectively operated-from the linefinder-district link for operating the multicontact relays in accordancewith the test made by the link for determining which party on a callingline has initiated a particular call. The common connector circuit isalso provided with a group of zone recording relays to which the zonerecord 1s transferred from the timing switch circult and which control,through an impulsing device, the application of one or more impulses tothe party line message register selected. These impulses are appliedthrough the line finder-district link over a line finder brush to themessage register terminal of the calling line.

Briefly, the invention functions in the following manner: After thecalling subscribers line has been extended to the line finderdistrictlink by the line finder, a test is made to determine which party on theline has initiated the call and a. record of such test is made in thelink. After the calling line has become extended to the called line andthe called subscriber has answered, the timing switch functions to causethe association of the common message register connector circuit withthe link and to transfer the zone record which has been set up in thetiming switch circuit through the operation of the sender and districtselector sequence switch to the zone recording relays of the commoncircuit. The party designation is at this time also transferred from thelink to the common circuit.

The common register connector circuit thereupon proceeds through theoperation of its multi-contact relays to connect with the terminals ofall message registers of the group of 400 lines in which the callingline is located corresponding to the party on the calling line who hasinitiated the call and to establish a. message register operatingcircuit extending from operating battery through the link circuit over abrush and terminal of the line finder to the other terminal of themessage register of the calling line party. Since the line finder canconnect with but one register terminal at a time, an operating circuitfor only the register of the calling line substation is effective.

In accordance with the zone record set up in the common circuit, theselected message register is variably operated to charge thev callingparty for the initial period of conparty register to charge for anovertime period of conversation. As soon as this charging is" completedthe timing-switch is advanced to dismiss the common circuit and tomeasure off a second period for conversation. In this manner the timingswitch advances through successive cycles until the connection isreleased. In the embodiment of the invention illustrated, the overtimeperiods measured vary in accordance with the zone in which the calledline terminates-and differ from the initial period measured on the samecall.

A clearer conception of the scope and purpose of the invention will beobtained from a consideration of the following description in connectionwith the attached drawings in which;

Fig. 1 shows a calling subscribers line having two party substationsthereon together with certain relays common to groups of callinglines;

Fig. 2 showsa start circuit and a of two link circuits;

Figs. 3 and 6 taken togetherv show a line finder-district link circuit,Fig. 3 showing the line finder and Fig. 6 the district selector;

Fig. 4 shows'a link circuit for associating a sender with the districtselector;

Fig. 5 shows a skeletonized disclosure of a register sender;

Fig. 7 shows in schematic form selectors for completing a connection toan automatic subscribers line, to a manual oflice or to an operatorsposition; I

Fig. 8 shows a timing switchindividual to the line finder-districtselector link of Figs. 3 and 6 for measuring the initial and overtimeperiods of conversation allotted to a calling subscriber for calls todifferent zones of the exchange area, and for seizing the common messageregister connector circuit;

Figs. 9 and 10 taken together show a common message register connectorcircuit for connecting the message register of a calling party linesubstation into an operating circuit and for controlling the manner inwhich the connected message register shall .be operated for calls todifferent zones; I

Fig. 11 shows the manner in which Figs. 1 to 10 should be .arranged tocompletely disclose the invention.

portion versation. As soon as this charging is com- The invention hasbeen embodied in a displeted the timing switch is advanced to dismissthe common circuit and under the control of a timing interrupter tomeasure off a period of time prescribed for the initial period ofconversation, which period may differ in accordance with the zone of theexchange area into which the connection has been extended. If theconversation continues at the end of this period, the timing switch iscaused to start upon a second cycle, again seizing the common registerconnector circuit and causing the operation of .the calling closurewhich is similar to that of U. S. Patent 1,567,072, granted'to W. H.Matthies, December 29, 1925, both the present disclosure and that of'theMatthies patent showing a skeletonized sender substantially the same asthat disclosed in the more complete disclosure of U. S. Patent1,589,402, granted to O. H. Kopp, June 22, 1926, and reference to theKopp patent is made for operations not completely described herein.

As disclosed in the above mentioned patentsa plurality of link circuitsisarranged to serve a group of calling lines'and are taken into servicein rotation. When a link circuit completes its function it hunts for andassociates itself with a district selector which is ready for use andthe link and district remain in a sub-allotted condition until the nextl nk inthe series has been put into service. The link circuit is thenput into an allotted position from whichit'will be advanced by theinitiation of a call and the action of the start circuit of Fig. 2. Thetrip circuit of Fig. 1 and start circuit of Fig.2 areso arranged thatonly one line may be served at a time and so that there may becooperatimi between two groups of lines to each of which a group of linkcircuits is individual. The details of these functions are described inthe above mentioned Matthies patent and since they form no part of thepresent invention will be omitted from the following description.

Establishment of a connection from substa- V at substation J firstinitiates a call for line 700 in zone 5 of the exchange area for whichhe is to be charged five times for the' first three minutes of'conversationand once for each one minute overtime period ofconversation. When the subscriber at substation J removes his receiverfrom the switchhook a circuit is closed from battery through the windingof relay 101, back contact of relay 102, over the subscribers line toground at the outer contact of relay 102. Relay 101 in operating closesa circuit from battery, winding of relay 103, right back contact ofrelay 104 to ground at the outer front contact of relay 101. It alsoprepares a circuit from battery through resistance 111 and the rightwinding of marginal relay 109 in parallel, inner front contact of relay101 to conductor 114, to identify the calling line to the line finder.Relay 103 in operating closes a circuit from battery over the backcontact of relay 201, conductor 130, right winding of relay 108, innerback contact of relay 107, back contacts of relay 109, middle leftcontact of relay 103 to ground. 7

Relay 108 operates in this circuit and closes a locking circuit foritself from battery through the right winding of relay 201, conductor129, over back contacts of relays similar to relay 108 individual toother groups of lines appearing before the same line finder, inner leftfront contact and left winding of relay 108, the right back contact ofrelay 109 to ground at the middle left front contact of relay 103. Relay108 prepares a circuit from groun at its outer right contact through thewinding of trip magnet 303 of the line finder to battery in preparationfor tripping the proper set of brushes when the line finder is operated.Relay 201 operates in the locking circuit of relay 108 and in combmationtherewith closes a circuit from ground over its outer right contact,conductor 128, inner right contact of relay 108, winding of relay 110 tobattery. Relay 110 locks over its inner right contact, the left backcontact of relay 109 to ground at the middle left front contact ofrelay. 103. Relay 110 closes a starting circuit for the allotted linefinder.

Assuming that the link and line finder shown are the ones to be usednext, sequence swltch 400'willbe standing in position 1 and sequenceswitch 600 in position 2. The op eratlon of relay 110 will thereforeclose a. circult from ground at its outer right contact, outer leftfront contact ."of relay 108, inner left front contact of relay 103,conductor 131, left back contact of relay 202, inner left back contactof relay 203, conductor 206, upper left and lower right contacts of cam403, brush 402 and terminal 401, conductor 378,

i upper left contact of cam 601, lower left conpact of cam 602, windingof relay 302 to batery.

Relay 302, upon operating, closes a circuit from battery through thewinding of updrlve magnet 304 of the line finder, outer right contact ofrelay 302 and in parallel through the winding of relay 300, uppercontacts of cam 603, inner left front contact of relay 302 to ground atthe lower left contact of cam 604. Relay 302 also locks over its innerright front contact, the upper left and lower right contacts of cam 605,the back contact of relay 305 to ground over commutator segment 306 andbrush 307. The line finder moves upwardly under the control ofmagnet 304and since trip magnet 303 is operated, the proper set of brushes istripped. The operation of relay 300 at its right back contact removesground from the line finder brush 326 during hunting, and prepares acircuit which is closed as soon as commutator brush 308 engages segment309 which extends from ground on brush 308, outer left contact of relay300, conductor 404, contact 230 of key 204, inner right front contact ofrelay 201 to conductor 129 and the right. winding of relay 201. Thiscircuit shunts the winding of relay 108 and causes that relay torelease, in turn, releasing the trip magnet 303. W hen the brush 308leaves segment 300 the circuit of relay 201 is opened and that relayalso releases. When line finder brush 381 makes contact with terminal380 which is connected over conductor 114 to battery, a circuit iscompleted over conductor 310, the upper left and lower right contacts ofcam 803, conductor 311, winding of relay 305, conductor 312, lower rightand upper left contacts of cam 804, conductor 805, outer left backcontact of relay 301, conductor 31.3 to ground over the lowe left andupper right contacts of cam 606. "Relay 305 operates in this circuit andcloses a shunt around its winding from ground over commutator brush 307and segment 306, front contact of relay 305, conductor 313, resistance806, lower contacts of cam 803, thence as traced through 5 the windingof relay 305 to ground at cam 606. This shunt circuit reduces theresistance in series with the winding of marginal relay 109 sufficientlyto cause .that relay to operate and to open the locking circuit of relay110 which, in turn, opens the energizing circuit of relay 302. Theoperation of relay 305 also opens one locking circuit of relay 302causing that relay to release as soon as the line finder brushes becomecentered on the terminals of the calling line and commutator brush 314engages an insulating portion of centering segment 315. The release ofrelay 302 opens the circuit of updrive magnet 304 to arrest the huntingmovement of the line finder and opens the circuit of relay 300.

At the time relay 300 operated it closed a circuit from ground at itsinner left contact over conductor 379, terminal 407 and brush 406 offinder 410, lower contact of cam 408, winding of relay 409, resistance411 to battery. Relay 409 operates and-closes a circuit from batterythrough the winding of sequence switch magnet 400, upper contact of cam412 to ground at the outer left front contact of relay 409, advancingthe link sequence switch 400 to position 2. When the switch 400 leavesposition 1, relay 409 releases. In position 2 a circuit is closed frombattery, through the winding of relay 413, the upper contacts of cam414, right back contact of relay 415 to ground at the lower rightcontact of cam 416. Relay 413 operates closing a circuit from batterythrough the left winding of relay 417, left front contact of relay 413to ground at the left back contact of relay 415. Relay 417, inoperating, closes a circuit from battery through the winding of updrivemagnet 418 of the sender finder 420, left contact of cam 479, outerright front contact of relay 417 to ground at the left back contact ofrelay 409. The sender finder moves upwardly under the control of magnet418 in search of an idle sender.

Relay 413 also closes a circuit from battery through the right windingof relay 415, the upper right and lower left contacts of cam 421, middlewinding of relay 415 to ground at the right contact of relay 413. Thecurrent in this circuit, however, is not sufficient to operate relay 415but does create a flux in its magnetic circuit so that it becomes quickto operate when the test circuit is later closed. The test circuitextends from brush 422, over the lower contacts of cam 419, the rightback contact of relay 409, the left winding of relay 415, the lowercontacts of cam 421, middle winding of relay 415 to ground at the rightcontact of relay 413.

An idle sender is characterized by battery connected to conductor 502.When, therefore, brush 422 engages terminal 423 corresponding to thesender of Fig. 5 which is assumed to be idle, the test circuit abovetraced is completed over terminal 423to battery and relay 415 operatesquickly. Relay 415, in operating, closes a locking circuit for itselffrom battery, through its right winding, upper right and lower leftcontacts of cam 421 to ground at the left front contact of relay 415. Italso opens the circuit of re-' lay 417 which releases to, in turn,release magnet 418 and bring the sender finder to rest on the terminalsof the idle sender. The release of relay 417, in turn, releases relay413. With relay 413 released and relay 415 operated, a circuit is closedfrom battery through the winding of sequence switch magnet 400, lowerleft contact of cam 476, contact 427 of jack 428, left back contact ofrelay 413, right front contact of relay 415 to ground at the lower rightcontact of cam 416, advancing sequence switch 400 to position 3. Whenthe link circuit advanced into position 2 for hunting for an idlesender, a circuit was closed for relay 318 extending from battery, rightwinding of relay 318', lower right contact of cam 610, upper rightcontact of cam 611, conductor 375, terminal 477 and brush 478 ofdistrict finder 410 to ground at the upper right contact of cam 429.Relay 318 locks over its inner right front contact and the uppercontacts of cam 606 to ground. A circuit is now established foradvancing sequence switch 600 into position 3 which may be traced frombattery through magnet 600, the lower right contact of cam 612, the leftfront contact of relay 318, conductor 319, lower contacts of cam 807,conductor 808, the left back contact of relay 302 to ground at the lowerleft contact of cam 604. 5 As the sequence switch 600 advances fromposition 2 to 3, relay 318 releases. l Vith sequence switch 600 inposition 3, busy ground is applied to the sleeve conductor 112 of thecalling line over line finder brush 326, right back contact of relay300, resistance 317, inner lower back contact of relay 316 conductor 812to ground at the upper left contact of cam 607. Cut-off relay 102 of thecalling line operates over this circuit releas- 115 ing line relay 101which,-in turn, removes battery from conductor 114, thereby releasingrelay 305. With sequence switch 600 in position 3 a circuit isestablished from battery through the winding of relay 322, resistance323, lower right contact of cam 601, upper right contact of cam. 602,segment 335 and brush 336 to ground for testing the sensitivity of testrelay 322. Relay 322 should operate at this time and upon operatingestablishes a circuit for relay 324 extending from battery through thewinding of relay 324, outer left back contact of relay 325 to groundatthe contact of relay 322. Relay 324 upon operating looks over. its innerright relays 316 and 329, brush 334, terminal 333,

front contact to ground at the lower left contactof cam 617. If relay322 does not operate the call is blocked and an alarm signal is given.

\Vhen sequence switch 400 reaches positlon 3 a circuit is closed fromground through the left and middle windings of relay 503, back contactsof relays 504 and 505, conductor 506, terminal 430. brush 431. rightcontact of cam 434, brush 432, terminal 433, conductor 314, lowerleftand upper right contacts of cam 613, assuming that the districtselector sequence switch 600 has new advanced to posltion 3, through thewinding of relay 351 to battery and in parallel over the lower contactsof cam 613 to battery through the lower winding of relay 316. Relay 316is marginal and does not operate but relay 315 operates althoughineffective at this time. Relay 503 operates and closes an obviouscircuit for relay 507 which, in turn, closes a circuit for relay 509.Relay 509 operates relay 510.

As soon as sequence switch 400 arrived in position 2 it prepared apulsing circuit for receiving dial pulses. This circuit may be tracedfrom battery through the left winding. of relay 500, conductor 537,terminal 440, brush 441,- lower contacts of cam 429, brush 47 8,terminal 477, conductor 375, left contact of cam 615, upper backcontacts of conductor 116, through the subscribers substation conductor117, terminal 332,. brush 331, outer lower back contacts of relays 329and 316, winding of relay 320, left contacts of cam 617, conductor 382,terminal 442, brush 443, upper right and lower left contacts of cam 403,brush 444, terminal 445 to ground at the back contact of relay 513.Relay 500 operates in turn operating relay 518 in the well-known manner,relay 518, in turn, operating relay 519. A circuit is thereupon closedfrom the source of tone 516 through the right winding of relay 500,switch 520 in normal position, front contact of relay 519, contact ofcam 514 to ground at the front contact of relay 509. This tone istransmitted to the calling subscriber to inform him that the sender isready to receive impulses which he may then send by manipulating hisdial.

\Vhen relay 510 operated it removed battery from conductor 502releasingrelay 415. \Vith relay 415 released, a circuit is closed from battery,through the winding of sequence switch magnet 400, upper left contact ofcam 476, right back contact of relay 415 to ground at the lower rightcontact of cam 416 for advancing sequence switch 400 into position 5.Sequence switch 400 remains in position 5 throughout the furtheroperation of the sender. The calling subscriber now proceeds to dial thedesired line number for setting the registers and translator of thesender in the well-known mannerr After dialing the first digit theswitch, the wlper of which is shown at 520, advances from normal closinga circuit extending from battery through the winding of relay 517,terminals and wiper 520, contacts of relay 519, contact of cum 514 toground at the outer right contacts of earn 509. Relay 517 closes anobvious circuit for relay 521.

As soon as the code registers of the sender have been set in accordancewith the first two digits dialed by the calling subscriber, thetranslator is set in a manner described in the aforementioned patent toO. H. Kopp. When the translator assumes its setting, 're-' lay 533operates and circuits are prepared over the translator are 534, througha back contact of relay 535 for operating either relay 536 or relay 547.or neither of them dependent upon in which zone of'the exchange thewanted line is located. For example, vif a called number isvdialed foreither zone 0 or zone 1, neither relay 536nor 547 will be operated. If acall is dialed for either zone 2 or zone 3, relay 536 will be operatedand if the call is for either zone 4 or zone 5, relay 547 will beoperated. It will be assumed that a call is for a subscribers lineterminating in the fifth zone and that therefore relay 547 is operatedover a circuit extending from battery, winding of relay 547, backcontact of relay 535, translator are 534 to ground at the contact ofrelay 533. Relay 547 locks over its left front contact, the contact ofcam 514 to ground at the outer right front contact of relay 509 andextends its locking ground to the winding of relay 538. Relay 538 uponoperating establishes a circuit from ground at the outer right contactof relay 509 over the contact of cam 514, the contact of relay 538 tobattery through the winding of relay 535. Relay 535 operates opening theinitial energizing circuit of relay 547 and connecting the translatorare 534 over a cable 539 to the class switch 540, which isdiagrammatically indicated in the upper right portion of Fig. 5. Theclass switch is thereupon set from the are 534 of the translator. Withrelay 547 operated and relay 536 non-operated, a circuit is preparedextending from battery through low resistance 549, right front contactof relay 547, right back contact of relay 536, the contacts of cams 541and 542, these cams being closed during the district brush selectionpositions of the sequence switches associated with the sender, conductor543, terminal 439, brush 438, right contacts of cam 405, brush 406,terminal 407, conductor 379 to the upper right contact of cam 609.

This circuit is completed as will be hereinafter described when thedistrict sequence switch is advanced to position 4, through the lowerwindings of zone relays 809 and 810 of the timing circuit of Fig. 8 forindicating the fact that the subscriber has made a call to a particularzone of the exchange, in the case assumed, the fifth zone. It may benoted at this time that due to the inclusion of the lowresistance 549,both zone relays 809 and 810 will operate. Had relay 536 been operated,then battery through highresistance 548 would have been connected overthe circuit just traced and only relay 810 would then be operated assoon as the district sequence switch reaches position 4. -If neitherrelay 536 nor 547 operate, then direct ground is connected to thecircuit prepared through the windings of relays 809 and 810 and neitherof the latter relays will operate.

With sequence switch 600 in position 3 relay 318 is energized over acircuit extending from battery through its right winding, the lowerright contact of cam 610, the lower left contact of cam 611, conductor378, terminal 401 and brush 402 of district finder 410, the leftcontacts of cam 435, brush 436 and terminal 437 of sender finder 420,conductor 542, the contact of relay 521, the back contact of relay 504,right contact of cam 526, Winding of sender stepping relay 522, backcontact of counting relay 525, left winding of overflow relay 523, leftcontact of cam 527, resistance 530 to ground. Relays 522 and 318operate, relay 318 looking over its inner right front contact, the upperleft contact of cam 610, thence over the circuit traced, whereby itremains energized as the sequence switch 600 advances into position 4.Relay 318 also closes a circuit to advance sequence switch 600 intoposition 4, extending from battery through the winding of magnet 600,lower right contact of cam 608, the outer right front contact of relay324, the left front contact of relay 318, conductor 319, the lowercontacts of cam 807, conductor 808, left back contact of relay 302 toground at the lower left contact of cam 604. As sequence switch 600advances out of position 3, relays 322 and 324 release.

When the district sequence switch 600 reaches position 4 for controllingbrush selection, the circuit previously traced from the contact of relay547 and extending to the upper right contact of cam 609 is extended overthe upper left contact of this cam, conductor 811 to ground through thelower windings of zone relays 809 and 810. These relays operate and lookover their upper windings and inner upper front contacts, conductor 812to ground at the upper left contact of cam 607.

The district selector is now controlled by the sender in its brush andgroup selection movements and then proceeds to hunt for an idle trunk inthe Well-known manner. After an idle trunk is selected a circuit isestablished in position 9 of sequence switch 600 for relay 318,extending from battery through its left winding, the lower contact ofcam 618, the lower left contact of cam 601,

the iimer left back contact of relay 324 to ground at the left frontcontact of relay 351. clay 318, upon operating, advances sequence switch600 into position 10 over a circuit extending from battery, winding ofmagnet 600, lower right contact of cam 612, left front contact of relay318, conductor 319, lower contacts of cam 807, conductor 808, left backcontact of relay 302 to ground at the lower left contact of cam 60 Inposition 10, relay 318 remains energized over the circuit previouslytraced. In position 10 which is the selection beyond position of thedistrict selector sequence switch, the control of succeeding switches iseffected over a fundamental circuit which may be traced in part vfrombrush 621, the upper right and-lower left contacts of cam 622, the rightback contact of relay 321,

conductor 378, thence as traced to the sender through the windingsofrelays 522 and 523, cam 546, brush 544 and compensating resistance 545,the back contact of relay 524, the right front contact of relay 507,conductor 543, terminal 439 and brush 438, the right contacts of cam405,

brush 406, terminal 407, conductor 379, the

right contacts of cam 624 to brush 625.

As soon as the selections are completed and the connection has been setup to the called subscribers line, reversed battery from the incomingselector 701 operates relays 522 and 523 in the usual manner and theserelays, in turn, cause the operation of the relays 531, 524 and 504.lVith these relays operated, the sender sequence switch is advanced toposition 18 for controlling talking selection. Relay 315 is operated inparallel with the lower winding of relay 316 throughout selections. Theoperation of relay 504, above mentioned, now opens a shunt around theright winding of relay 503 including that winding in the circuit ofrelays 351 and 316. Relay 35 1 thereupon releases, in turn, opening thecircuit of relay 318 which also releases. Upon the release of relay 318the district sequence switch 600 is advanced into position 11 over acircuit extending from battery, winding of magnet 600, upper leftcontact of cam 608, left back contact of relay 318, thence as traced toground at the lower left contact of cam 604. As the sequence switchenters position 11 ground is connected to conductor 314 at the lowerright contact of cam 617, over terminal 433, brush 432, upper contactsof cam 446, left winding of relay 415, right back contact of relay 409,lower contact of cam 434, brush 431, terminal 430, conductor 506, leftback contact of relay 505, windings of relay 503. Since these windingsare also connected to ground, relay 503 now releases, in turn, releasingrelay 507. The release of relay 507 does not release relay 509 sincethat-relay is locked to its own front contact. A circuit ft contact toconround as above traced.

locks over its middle ductor 506 and to After leaving position 10, relay316 is disconnected from conductor 314.

With sequence switch 600 in position 11 the subscribers line becomesdisconnected fromthe sender at contacts of cams 615 and 617 and relay329 is operated in a circuit extending from battery, through its upperwinding, the upper back contact of relay 330, the lower right and upperleft contact of earn 619 to ground at the upper right contact of cam617. Relay 329 upon operating extends its operating circuitover itsmiddle upper front contact to battery through the winding of relay 338which operates. At its inner right and left front contacts relay 338connects the winding of relay 322 to the tip-and ring conductors 116 and117 of the calling line, and establishes a holding circuit from groundat its middle left contact through the lower winding of relay 329 toinsure that rea lay 329 will remain operated until after relay (iii 338has released to disconnect relay 322 from conductors 116 and 117. At thetime relay 329 operated the operating ground therefore is also connectedto the cam Contact of interrupter 339 and thence as soon as interrupter339 closes its lower contact to battery, through the right winding ofrelay 340. Relay 340 operates and locks over its inner right frontcontact to the operating ground independently of interrupter 339 and assoon as interrupter 339 makes its upper contact, establishes a circuitfor relay 302 extending from battery through the winding of relay 302,middle right front contact of relay 338, outer rightfront contact ofrelay 340, upper contact of interrupter 339, thence to ground as tracedat the upper right contact of cam 617. Relay 302 upon operating locksover its inner right front contact to ground at the lower front contactof relay 329 and at its inner left front contact establishes a circuitfor advancing sequence switch 600 into position 12. This circuit extendsfrom battery through the winding of magnet 600, the upper left contactof cam 612, conductor 620, the upper right and lower left contacts ofcam 801, conductor 802, the inner left front contact of relay 302 toground at the lower left contact of earn 604. Upon leaving position 11%the operating circuits of relays 329 and 338 and the holding circuit ofrelay 340 are "opened and relays 338 and 340 release. Re-

lay 338, upon releasing, opening the holding circuit of relay 329 whichin turn releases, opening the holding circuit of relay 302. It has beenassumed that the substation J has initiated the call and that thereforewhen relay 322 was connected to the calling line conductors upon theoperation of relay 338 it did not operate as the operating ground atsubstation J extends through the substation bell and a condenser. Sincerelay 322 did not operate 'no circuit was established thereby foroperating the message register switching relay 324 and therefore thefact that relay 324 is not operated registers in the districtcircuit'that the party J has initiated the call. Had the party Winitiated the call then when the test relay 322 is connected to the lineconductors the circuit of relay 322 is completed-through the substationbell of the substation W to ground, and relay 322,

upon operating, operates relay 324 which then looks over its inner rightfront contact to ground at the lower left contact of cam 617,registering the fact that the party W has initiated the call.

Talking selection With sequence switch 600 in position 12 the callingsubstation is connected in a talking path extending from groundthroughthe upper left winding of repeating coil 631, lower right contactof cam 615, upper back contacts of relays 316 and 329, brush 334,terminal 333, line conductor 116, through the calling substation J, lineconductor 117, terminal 332, brush 331, lower back contacts of relays329 and 316, winding of supervisory relay 320, upper contacts of cam 617to battery through the lower left winding of coil 631. Relay 320operates in this circuit and remains operated until the callingsubscriber hangs up and establishes a circuit for relay 301 extendingover the contact of relay 320, the upper right and lower left contactsof cam 605 to ground at commutator brush 336.

A circuit is also established for relay 318 extending from batterythrough its right winding, the lower right contact of cam 610, lowerleft contact of cam 611, conductor 378, terminal 401, brush 402, leftcontacts of cam 435, brush 436, terminal 437, conductor 542, frontcontact of relay 521, front contact of relay 504, right contact of cam526, the sender sequence switch being in position 18 for talkingselection, windings of relays 522 and 523, right contact of cam 527,right back contact of relay 507 to ground through resistance 530. Relays318 and 522 energize relay 318 closing a circuit extending from batterythrough sequence switch magnet 600, the lower right contact of cam 612,the left front contact of relay 318, thence to ground at the lower leftcontact of cam 604, as previously traced. Relay 318, upon energizing,locks over its inner right front contact, the upper left contact of cam610, thence over the fundamental circuit as traced. As sequence switch600 rotates out of position 12 toward position 16, ground isintermittently connected to the fundamental circuit in shunt of senderstepping relay 522 over the upper contacts of cam 606. When the senderis satisfied as to its talking selection setting, the fundamentalcircuit is opened at the sender through the operation of relay 525.Relay 318 deenergizes arresting sequence switch 600 in its next stoppingposition, The sequence switch may be arrested in any one of threepositions, position 13, which is a charging po sition for connections tozones 0, 2 and 4, po-

- sition 14 which is a charging position for connections to zones 1, 3and 5 and position 15 for connections to an operators position. Since ithas been assumed that the calling subscriber has made a call to zone 5of the exchange, the district selector sequence switch will be arrestedin talking selection position 14.

. At the sender after. talking selection is completed relay 515 operatesconnecting battery to conductor 506 in parallel with the winding ofrelay 505. The current in this circuit is now suificient to operaterelaiy 415 which closes a circuit from battery through the left windingof relay 417, left contacts of cam 421 to ground at the left frontcontact of relay 415. Relay 417 closes a circuit from battery throughthe winding of sequence switch magnet 400, upper contact of cam 479,outer right front cont-act of relay 417, left back contact of relay 409to ground, advancing sequence switch 400 to position 6. In this positionall the conductors extending to the sender are opened and the sender iscompletely released. As soon as sequence switch 400 leaves position 5relay 415 releases and, in turn, releases relay 417 unless the senderfinder 420 is standing on one of its top ten terminals. If the lattercondition exists relay 417 is held operated in a circuit from batteryover its left winding and left front contact, upper left contact of cam424, commutator segment 464, brush 463 to ground. With relay 417operated at this time a circuit is closed from battery throughresistance 411, winding of relay 409, lower contact-s of cam 414, innerright front contact of relay 417, lower right contact of cam 416 toground. Relay 409 looks through its inner left contacts to ground at thelower confacts of cam 467 and also closes a second locking circuit forrelay 417. lVith relay 409 operated a circuit is closed from batterythrough the winding of downdrive magnet 465 of the sender finder 420,left contact of cam 412 to ground at the outer left front contact ofrelay 409. When the sender finder reaches its lowermost position acircuit is closed from ground, over brush 463, bottom commutator segment406, lower right contact of cam 456 to resistance 411. shunting thewinding of relay 409 and causing that relay to release, in turn,releasing relay 417. With relay 417 released, in position 6 a circuit isclosed from battery through the winding of sequence switch magnet 400,lower right contact of cam 476, right back contact of relay 417 toground at the lower right contact of cam 416, advancing sequence switch400 to position 7.

When sequence switch 400 reaches position 7, thelink circuit is ready toassociate itself with another district selector which is standing inposition 1 awaiting association. with a link and a circuit will beclosed from ground over the upper right contact of cam 617, the

upper left contact of cam 619, the lower right contact of cam 623,contacts 341 of jack 340, conductor 392, contact of jack 448, contact ofjack 449, upper right contacts of cam 416, right back contact of relay415, upper contacts of cam 414, winding of relay 413 to bat- U tery.Relay 413 closes a circuit from battery through the left winding ofrelay 417, left front contact of relay 413'to ground at the left backcontact of relay 415. Relay 417 in operating closes a circuit forupdrive magnet 447 of the district finder 410, lower right contact ofcam 479, outer, right front contact of cuit extends from conductor 366,terminal 450, brush 451, contact of ack 449, upper left and lower rightcontacts of -cam 419, right back contact of relay 409, left winding ofrelay 415, lower contacts of cam 421, middle winding of relay 415, toground at the right contact of relay 413.

If the district selector for which the finder 410 is hunting does notlie between the last. position occupied by the finder and the top of thebank, it will continue to move upwardly until brush 453 engages segment452, completing a circuit over the upper right contact of cam 408,Winding of relay 409, resistance 411 to battery. Relay 409 opens thetest circuit, opens the circuit of updrive magnet 447 and closes acircuit from battery through the winding of downdrive magnet 454, lowercontact of cam 412, left front contact of relay 409 to ground. Thefinder 410 is restored to its lowermost position under the control ofmagnet 454 at which time a. circuit is closed from ground over brush453, bottom segment 455 of the finder commutator, upper right contact ofcam 456, resistance 411 to battery, shunting and releasing relay 409which restores the test circuit and the circuit of updrive magnet 447.When brush 451 enco unters terminal 450 to which conductor 366 extendsthe test circuit is completed and relay 415 operates, locking throughits right winding, the upper right and lower left contacts of cam 421 toground at its outer left" front contact, opening the circuit of relay417 to deenergize magnet 447 and to bring the finder 410 to reston theterminals of the district selector. With relay 415 operated and relay417 released a c1rcuit is closed from battery through the winding ofsequence switch magnet 400, lower left contact of cam 476, contact 427of ack 428, the left back contact of relay 413, right front contact ofrelay 415, upper contact of ram 416, contacts of jacks 449 and 448 toground on conductor 392, advancing sequence switch 400 to position 8.

Relay 415 is held operated in position 8 from battery at the districtselector over terminal 450, brush 451, contacts of jack 449, upper leftand lower right contacts of cam 419, back contact of relay 409, leftwinding of relay 415, lower contacts of cam 421 to ground at the leftfront contact of relay 415. lVith relay 415 operated a circuit is closedfrom ground at the right lower contact of cam 416, right front contactof relay 415, the upper left contact of cam 429, brush 47 8, terminal477, conductor 37 5, upper right contact of cam 611, lower right contactof cam 610 to battery, through the right winding of relay 318. Relay 318operates and closes a circuit from battery through the winding ofsequence switch magnet 600, lower right contact of cam 612, left frontcontact of relay 318, conductor 319, lowergontacts of earn 807,conductor 808, left back contact of relay 302 to ground at the lowerleft contact of cam 604, sequence switch 600 advancing to position 2,releasing relays 3l8and 415. Relay 415, upon releasing, closes a circuitfrom battery through the winding of sequence switch magnet 400, upperleft contact of cam 476, right back contact of relay 415 to ground atthe lower right contact of cam 416 for advancing sequence switch 400 toposition 9. The link circuit remains in this position until the linkstanding next to it in the series is advanced from position 1 for thepurpose of selecting a sender. Link circuit 260 occupyingthatrelationship to the link circuit of Fig. 4 a circuit may be traced fromground over the lower contact of cam 261, the right.

contact of cam 262, conductor 263, contact 460 of jack 428, rightcontacts of cams 461 and 462 to battery through the winding of sequenceswitch magnet 400, advancing the sequence switch to position 10 which isthe equivalent of position 1 so that the link circuit is ready tooperate in response to the next call in the group of lines servedthereby.

Making initial charge for a call in zone 5 of the exchange area It willbe recalled that for a call into 'zone 5 of the exchange area thedistrict sequence switch 600 was arrested in talking position 14 andthat both zone relays 809 and 810 have been operated and locked. Whenthe called subscriber 700 responds after the application of ringingcurrent to his line from the incoming selector 701, in the well knownmanner, relay 627 operates in a circuit which may be traced in part frombrush 621, the upper contacts of cam 622, the upper right winding ofrepeating coil 631, winding of relay 627, lower right winding of coil631, upper contacts of cam 624, to brush 625. erating, relay 627establishes a circuit from ground at the right contacts of cam 607,front contact of relay 627, upper contacts of cam 623, conductor 628,right contacts of cam 813, conductor 814, lower contact of inter raptor3-13, conductor 815, upper left and lower right contacts of cam 816,conductor 81.7, left winding of relay 340 to battery. Relay 340 operatesand looks over the circuit previously traced to conductor 814, thenceover the outer left front contact ofrelay 340, conductor 815, thence astraced to battery through the loft winding of relay 340. As soon asinterrupter 343 makes its upper contact, a circuit is established frombattery through the winding of sequence switch magnet 800, lower rightcontact of cam 818, right contacts of earn 819, conductor 822, uppercontacts of cam 618, conductor 630, inner left front contact of relay340, upper contact of interrupter 343, conductor 814, thence to groundas traced over the front contact of relay 627, to ground at the rightcontacts of cam 607 for advancing sequence switch 800 into position 2.Upon leaving position 1 the holding circuit of relay 340 is opened andrelay 340releases.

As soon as sequence switch 800 leaves normal, a circuit is establishedfor relay 325, extending from battery through the winding of relay 325,conductor 345, upper right and lower left contacts of cam 816, conductor831, to ground at the lower left contact of cam 617. Relay 325 uponoperating extends its operating ground to the winding of relay 321 overits inner right front contact, thereby operating relay .321 which looksitself and relay 325 over itainner left front contact to ground at thelower contacts of cam 607.

With sequence switch 800 in position 2, a start circuit is establishedfrom ground on conductor 628, over the lower left contact of cam 813,upper winding of relay 823, conductor 824, left back contact of relay1000, right back contact of relay 1001, right back contact of relay1002, winding of relay 1003, to battery at the back contact of relay1004, if the message register connector circuit of Figs. 10 and 11 is atthe time free. Relays 1003 and 823 operate and if the timing circuit ofFig. 8 occupies apreferential position with respect to other timingcircuits, relay 823 locks over its lower winding, the left contacts ofcam 825, the upper front contact of relay 823, conductor 826, right backcontact of relay 1000, winding of relay 1004, to ground at the left backcontact of relay 1002. Relay 1004 operates in this locking Uponopwinding of relay 1006.

obvious circuit for relay 1001 thereby connecting the start conductor824 over the left back contact of relay 1000, the right front contact ofrelay 1001 to ound through the operate at this time. Relay 827 .alsooperates in parallel with the locking winding of relay 823, extendingcommon operating leads 850 from the connector circuit tothe district;

selector circuit and at its middle upper front contact establishes acircuit from ground I over conductor 828, to battery through the windingof relay 344, thereby operating this relay. A circuit is now establishedeither for .relay 900 or relay 901 depending upon whether the party testrelay 324 was or was not operated. In the case assumed, relay 324 i wasnot operated and therefor with relay 344 operated, relay 900 is operatedover a circuit extending from battery, winding of relay 902, winding ofrelay 900, conductor 903, inner upper from contact of relay, 344, leftback contact of relay 324, lower frpnt contact of relay 344, lowercontacts of cam 605, commutator segment 335, brush 336 to ground. Hadrelay 324 operated through the initiation of a call by the party W, thenrelay 901 is operated from battery, winding of relay 902, winding ofrelay 901, conductor 904, upper front contact of relay 344, left frontcontact of relay 324, thence to ground as traced at brush 336. Relay 902being marginal does not operate in the circuit of either relay 900 orrelay 901.

With relay- 900 operated circuits are closed for five multi-contactrelays, one of which is shown at 905, and each relay 905 extends itsoperating circuit to a corresponding multi-contact relay 906. Eachmulti-contact relay, such as 905 and 906, controls operating circuitsextending to forty message registers, and thus as soon as five relayssimilar to relay 905 and five relays similar to relay 906 are operatedthrough the operation of relay 900, the message registers of allsubstations corresponding to the substation J of the 400 lines-appearingin the line finder in Fig. 3 are connected through the contacts of theserelays to the corresponding operating conductors of'the 400 linesterminating in terminals corresponding to terminal 380 appearing in theline finder bank. For example the circuit of message register 105 of thecalling party J may be traced in part from terminal 380, conductor 114,the back contact of line relay 101, conductor 106, the outer right frontcontact of relay 905, conductor 907 to ground through message register105. Had relay 901 operated, in turn operating five multi-contact relayscorresponding to relay 908 and in turn five multi-contact relays corelay1006 does not respondin to relay 909, then the message registers of a lsubstations corresponding to the substation W of the same 400 lineswould be connected to the operating conductors of the 400 linesterminating in terminals corresponding to terminal 380. For example, inthat case the circuit through message reg ister magnet 135 may be tracedin part from terminal 380, conductor 114, back'contact of line relay101, conductor 106, theouter right front contact of relay 908, conductor910 to ground through 'message register 135.

With either relay 900 or 901 operated, a

circuit is established from ground in parallel through back contacts ofmulti-contact relays controlled thereby to' battery through the windingof relay 911. Relay 911 operates and remains operated until all of themulticontact relays, such as 905, 906 which should operatehave operated,and at its left back contact opens the operating circuit 'of chargingrelay 1007 to prevent initiation of charging. In the event that bothrelays 900 and 901 operate erroneously, the marginal relay 902 willreceive current to operate and will in turn hold relay 911 operated toprevent charging.

Referring to the operation of the timing circuit of Fig. 8, it will berecalled that I sequence switch 800 is standing in position 2 and thatrelays 823 and 827 are operated. It will also be recalled that for callsto zones 0, 2 or 4, sequence switch 600 will be standing in position 13and that for calls to zones 1, 3 or 5 it will be standing in position14. A test is now'made of the continuity of common conductors 850extending through front contacts of relay 827 to the windings of zonerelays in the connector circuit. One of these test circuits extends frombattery through the winding of relay 913, winding of zone relay 914,conductor 835, upper front contact of relay 827, left contacts of cam834, to ground at the inner lower front contact of relay 810 if relay810 is operated, or over the inner lower back Contact of this relay, theleft contacts of cam 839 to ground at the lower front contact of relay823, if relay 810 is not operated. Another circuit extends from batterythrough the winding of relay 913, the winding of relay 915, conductor1010, the right back contact of relay 1008, conductor 836, the lowerfront contact of relay 827, the lower right and upper left contacts ofcam' 829 to ground at the upper front contact of relay 809 if it isoperated, or if it is not operated over its upper back contact throughthe left contacts of cam 839 to ground at the lower front contact ofrelay 823. If sequence switch 600 is in position 13, a circuit isestablished from battery, winding of relay 913, winding of zone relay912, con ductor 840, inner lower front contact of relay 827, leftcontacts of cam 842, upper front contact of relay 810, which is operated

